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1. Citation: Sherwani P, Vire A, Anand R and Aggarwal A. Utility of MR Imaging in Developmental Dysplasia of Hip.
Austin J Radiol. 2016; 3(3): 1052.
Austin J Radiol - Volume 3 Issue 3 - 2016
ISSN : 2473-0637 | www.austinpublishinggroup.com
Sherwani et al. © All rights are reserved
Austin Journal of Radiology
Open Access
Abstract
Developmental dysplasia of the hip is the most common cause of an unstable
hip in paediatric population. It can be assessed using various radiological
modalities. However due to excellent soft tissue characterization and with no
radiation hazards, Magnetic Resonance Imaging (MRI) plays an important role
in the early detection as well as in the evaluation of various soft tissue obstacles
that can cause hindrance in reduction. Preoperative MR imaging also helps in
determining the acetabular labral coverage which further guides the orthopaedic
surgeon in planning the management. In postoperative cases, apart from the
assessment of adequacy of reduction, immediate and delayed post operative
complications like ischemic necrosis can be detected earlier than with other
imaging modalities thus helping in appropriate and timely management. Here
we present a pictorial assay of the MR imaging techniques and the findings with
a focus on various important anatomical structures required to be evaluated
while performing and reporting MRI of these cases.
Keywords: Acetabulum; Complications; Computed tomography (CT);
Developmental dysplasia of hip (DDH); Magnetic resonance imaging (MRI);
Radiography
Introduction
Developmental Dysplasia of Hip (DDH), also termed as
infantile hip dysplasia is the most important cause of unstable hip
in children [1]. Left hip is more commonly involved (40 to 60% of
cases) with bilateral involvement in 20% [2]. It includes spectrum of
developmental disorders in which mild dysplasia refers to stable and
aligned hip while in severe cases the hip is unstable and dislocated
[3]. DDH occurs either due to the acetabular dysplasia or due to
the laxity of the supporting structures. The hip joint develops from
the cartilaginous anlage at around 4 to 6 weeks gestational age. The
femoralheadgetscompletelyencircledbytheacetabularcartilage.Due
to disproportionate growth of the femoral head and the surrounding
cartilage, less than 50% coverage of the femoral head occurs at birth.
However weeks after the birth, the acetabular cartilage develops more
rapidly than the femoral head which results in progressively increased
coverage [4]. Therefore minimal structural support of the femoral
head is during late gestation and few months after birth so there
are more chances of hip dislocation or subluxation in this period.
Intrauterine factors like oligohydrominos and post natal positioning
such as wrapping the legs in extended position affect the acetabular
development [5]. The Risk factors include positive family history,
breech presentation, torticollis, scoliosis and structural abnormalities
which include underdevelopment of anterior capsule, ligament
of Bigelow or rectus muscle [6]. Early diagnosis and treatment are
important as the acetabulum is susceptible for remodeling in the first
6 weeks.
Clinical tests play a major role in the early detection of DDH.
Imaging studies which include plain films, Ultrasound, CT and
MRI supplement the clinical tests both for diagnosis as well as for
follow up. Plain films are valuable in children >6 months after the
femoral head and acetabular ossification occurs. Ultrasound plays an
important role in the evaluation of acetabular morphology before the
Review Article
Utility of MR Imaging in Developmental Dysplasia of Hip
Poonam Sherwani1
*, Adweta Vire1
, Rama Anand2
and Anil Aggarwal3
1
Department of Radiodiagnosis, Chacha Nehru Bal
Chikitsalya Hospital, India
2
Department of Radiodiagnosis, Lady Harding Medical
College and associated Hospitals, India
3
Department of Orthopaedics, Chacha Nehru Bal
Chikitsalya Hospital, India
*Corresponding author: Poonam Sherwani,
Department of Radiodiagnosis, Chacha Nehru Bal
Chikitsalya Hospital, Geeta Colony, New Delhi, India
Received: May 30, 2016; Accepted: August 23, 2016;
Published: August 29, 2016
appearance of ossific nucleus and also in the dynamic examination.
CT has a limited role and is only done in postoperative cases for
assessment of adequacy of reduction when the patient is in spica
cast and ultrasound cannot be done [7]. To minimize the radiation,
low dose CT technique should be employed [8]. Due to better soft
tissue characterisation and no risks of ionising radiation, MRI is the
excellent modality to show the relationship of femoral head and the
acetabulum even when they are not ossified. It is preferred to look
for- the femoral ossific nucleus, the acetabulum, and the soft tissue
obstacles in the reduction in non reducible cases and also to look
for the immediate and delayed post operative complications like
ischemia which can be detected earliest on MRI.
Overview
MRI can be used in early detection and evaluation of DDH.
The femoral capital epiphysis displays intermediate signal on T1W
and hyperintense signal on T2W. Due to its multiplanar imaging
capability ,the position of the capital epiphysis can be demonstrated
on coronal imaging especially when it is uncertain on conventional
radiograph and the ossific nucleus is not visible on plain radiograph.
Axial and coronal MR images are most useful and small surface coils
with high spatial resolution are necessary to evaluate DDH. Essential
sequences include T1W for portraying the ossified elements with good
anatomical detail, T2W for effusion, PDFS to see for cartilage a s well
as labrum and dynamic Post contrast T1W FS for the early detection
of ischemia in post operative cases.MR imaging has numerous
advantages over radiography particularly in looking for the ossified
femoral nucleus as well as in better demonstration of morphology of
the acetabular dysplasia in single examination with lack of ionising
radiation. Also with the proper use of sequences arthrogram like
image can be produced [9]. MR is also used to evaluate the causes
of non reducibility in the preoperative imaging and also to detect
the immediate and delayed post operative complications. Aditi et al.

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[10] described the use of postoperative MRI after spica cast to look
for the successful reduction and also to see for the post reduction
complications.
However, limitations of MRI include high cost, need for sedation
in children due to long scanning time and lack of dynamic evaluation.
Also immediate post operative imaging cannot be done if the non
compatible MR implants are used.
In general, MRI is only indicated for complicated or severely
dysplastic hips and in post operative unsuccessful reduction and to
see for post operative complications [6].
MR Techniques and interpretation
Sedation is given in infants and younger children to optimize
the MR imaging technique and to avoid the motion artifacts. Proper
sedation guidelines are to be followed and commonly used sedatives
include barbiturates and fentanyl. Proper monitoring should be done
during and after the sedation.
For imaging and comparison of both the hips large FOV is
required for which body coil is used however dedicated Hip coil is
used to provide high resolution images. Examination is performed
with 512 x 256 or 256 x 256 acquisition matrix using 1 or 2 excitations
(NEX). Thin sections (3 or 4 mm) are used with minimal interslice
gap. Standard imaging protocols in hip includes coronal T1W Spin
echo, coronal short tau inversion recovery, axial T2 W Fast Spin
Echo (FSE), fat saturated oblique sagittal FSE, Proton Density (PD)
FS and axial FSE PD images. Additional protocols include coronal
three-dimensional spoiled gradient recall echo with fat suppression
and post contrast FS T1W.
Anatomy with normal MR appearance
Important anatomical structures to be evaluated and to be
reported in hip in DDH with their typical appearance on MRI are:
1. Acetabular Labrum: It is the fibro cartilaginous rim which
deepens the acetabular cavity. On routine MR imaging, the normal
labrum is seen as dark signal triangle covering the articular cartilage
at the peripheral margin of the acetabulum and are named according
to the location as anterior superior, superior and posterior superior
labrum (Figure1a and b).
2. Transverse acetabular ligament: The inferior aspect of the
acetabulumisnotcoveredwiththelabrumandthetransverseligament
spans the inferior acetabulum (Figure 2a). It shows homogeneous low
signal on spin echo and gradient echo images.
3. Ligamentum teres: It is the ligament which extends from the
acetabular fossa to the fovea capitis, a small depression on the medial
femoral head (Figure 2b).
4. Cartilage: The acetabulum is entirely covered by the articular
cartilage except for the acetabular fossa. Fovea capitis is the only aspect
of femoral head deficient in cartilage.It is thicker along the superior
margin of the femoral head and thinnest along the posterior margin.
It shows intermediate signal intensity on spin echo and gradient echo
images (Figure 3).
5. Capsule: Fibrous capsule attaches proximally to the acetabular
labrum, transverse ligament and extends to the most of the femoral
neck with attachment to the base of trochanter. Capsule is reinforced
by ischiofemoral, iliofemoral and pubofemoral ligaments which
are the thickening of the capsule. On routine MRI, capsule appears
hypointense on T1W and T2W images (Figure 4a).
6. Iliopsoas tendon: Major hip flexor which is inserted on lesser
trochanter and passes anterior to the hip joint (Figure 4b).
7. Pulvinar fat: Acetabular fossa is the inferiomedial part of the
acetabulum which is occupied by the pulvinar fat pad and the round
ligament.
Figure 1 a&b: (a) T1 W coronal image depicts normal superior (large
white arrow) and inferior acetabular labrum(small white arrow) (b) T2 W
sagittal image of left hip showing anterior (large white arrow)and posterior
labrum(small white arrow) which appear hypointense on both and are named
according to location.
Figure 2 a&b: (a) T2WFS Sagittal image of the left hip depicting normal
transverse acetabular ligament (large black arrow) and ligamentum teres
(small black arrow). (b) T2W FS axial view depicting the normal ligamentum
teres (white arrow).Note is made of right hip joint effusion.
Figure 3a: Axial T2W FS image of the pelvis including bilateral hips depicting
normal acetabular cartilage (white arrow) showing intermediate signal which
is deficient at the fovea capitis. Joint effusion is seen on right side. (b)
Zoomed image of the same better depicts the anterior and posterior articular
cartilage (arrow).

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Imaging findings in DDH
MR findings in DDH include:
1. Laterally displaced femoral head with superior and posterior
dislocation.
2. Changes in labrum which include thickened labrum, altered
signal intensity (Figure 5 a&b) or flipped labrum (Figure 6a)
3. Pulvinar hypertrophy (Figure 6b)
4. AP relationship and dysplasia of acetabulum and acetabular
dysplasia-which is measured by acetabular index (Figure 7).
Acetabular index measures the weight-bearing surface of the
acetabulum or sourcil. Sourcil represents the area of subchondral
osseous condensation in the acetabular roof. It is the angle sustained
between the horizontal and a tangential line extending from the
medial and lateral edges of the sourcil. Normal acetabular index is
equal or less than 15⁰
and more than 15⁰
is abnormal (Figure 7).
5. Interposition of ligamentum teres and iliopsoas tendon (Figure
8 a&b).
Essential sequences to be performed in DDH include:
1.Axial T1W: For the detailed anatomical evaluation and is best
in looking the ossific nucleus which show intermediate signal on
T1W and to see for pulvinar hypertrophy which looks hyperintense
on T1W.
2. Coronal T1W: for the displacement of femoral head and
acetabular dysplasia.
3. Axial T2W: To see for the complications associated with DDH
Figure 4a: Sagittal T2W FS image of left hip demonstrates the normal fibrous
capsule (arrow) appearing hypointense on all sequences and is reinforced by
multiple ligaments. (b) T2W FS axial image shows iliopsoas tendon (arrow)
as a low intensity structure which is a major flexor of hip joint and is inserted
on the lesser trochanter.
Figure 5 a&b: Right sided DDH STIR Coronal image (a) Head is dislocated
superiorly on right side (arrow). (b) Labrum is also thickened and appears
hyperintense (arrow).
Figure 6 a&b: STIR coronal image with right sided DDH. Femoral head is
displaced superiorly. Acetabular labrum is hypertrophied and slipped into the
joint (arrow) which blocks the closed reduction. (b) Axial T1W image with
DDH on right side shows pulvinar hypertrophy (arrow), another cause of
difficult reduction.
Figure 7: T1W coronal image of showing normal acetabular index on left side
and abnormal on right side.
Acetabular index is the angle between horizontal line through sourcil and line
through the acetabular roof.
Normal</= 15o
and >15o
is abnormal.
Sourcil-area of subchondral condensation in acetabular roof.
Figure 8 a&b: (a) Left DDH. T2W FS Coronal image showing the superiorly
displaced left femoral head with redundant ligamentum teres (large arrow)
and posterior capsule) (arrow) causes hindrance in reduction.
(b) Bilateral DDH. T2 W FS axial image depicting the interposition of iliopsoas
tendon on right side (arrow) another cause of failed reduction.

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like ischemic necrosis and joint effusion.
4. PD FS Coronal: To see for the interposed iliopsaos tendon,
labral changes and to evaluate the labral coverage beyond the lateral
margin of bony acetabulum relative to the femoral capital epiphysis.
5. PD FS Saggital image: To look for interposed iliopsoas tendon
which prevents the reduction?
6. Post contrast T1W FS: To see for the ischemic necrosis.
Failure of reduction
Possible hindrance in reduction include flipped labrum,
prominent pulvinar, redundant ligamentum teres, capsule or
iliopsoas tendon which may become interposed into the joint.
Role of MRI in management
The main aim of the treatment for DDH is the concentric closed or
open reduction of femoral head and to achieve the maximum stability
with a good anatomical and functional outcome using splint device.
However if the hip is unstable or non concentric, the additional
procedures such as debridement, capsulorraphy, acetabular and
femoral osteotomies can be performed. Coronal MR shows the
acetabular labral coverage beyond the lateral margin of bony
acetabulum relative to femoral capital epiphysis which is important in
determining the coverage of femoral head and the need for increased
coverage through osteotomy and conservative management if there
is proper coverage.
Patients with delayed diagnosis or patients who are refractory
to treatment, MR imaging is important in preoperative assessment
of femoral head deformity, acetabular dysplasia and femoral head
coverage by the bony acetabulum. DDH can also predispose to
osteoarthritis due to chronic stress on the labrum with chondral
injury [11].
MRI is also required in immediate post operative period after
reduction to assess for the adequacy of the reduction. As in young
infant, unossified nuclei are present so the joint space is not visible on
conventional x-ray. On MRI the ossific nucleus of the femoral head
should lie anterior to the line joining the triradiate cartilages after
reduction. Eimear et al reported the use of axial STIR MRI to confirm
the femoral head reduction in DDH [12].
Role in post reduction ischemia
As the infants are placed in abduction and flexion position in
spica cast for weeks after reduction, femoral head should be held in
safe zone as little abduction can result in redislocation and too much
abduction can cause Avascular Necrosis (AVN) which can further
lead to proximal femoral growth deficiency. The blood supply to the
femoral head is through circumflex femoral vessels which enter the
femoral epiphysis and ramify in the femoral head. Incidence rate
of AVN is upto 47% [13]. Post reduction CT can be done to see for
the femoral head position, however non ossified nucleus cannot be
visualised and vascularity cannot be detected which are important
in determining the completeness and the safety of the reduction.
Moreover radiation is also a concern. Tailored approach can be done
to evaluate for the ischemia which includes coronal Fast gradient
echo localiser images, axial spin echo T1W images before contrast
administration and dynamic post contrast FS T1W images after
contrast administration [6]. Images are obtained at section thickness
of 4mm and a section gap of 1mm.Average duration of is sequence is
1 min 30 sec. The sequence was obtained repeatedly for an interval of
5-10 min. Enhanced epiphysis and physis vascular phase is obtained.
Ischemic changes in the femoral head are either seen as diffuse
hypoenhancing without focal abnormality or focal areas of decreased
enhancement. The anterolateral head is more prone for ischaemia.
The avascular zone is well demarcated area and is geographic and is
easily demonstrated on imaging.
Salter and colleagues classified avascular necrosis as either
asymmetric or focal or diffuse on dynamic enhanced MRI. MR
showing global decrease in enhancement showed ten times more
chances of developing AVN [14].
MRI can detect the ischaemic areas at the earliest when it is still
reversible [15].
Delayed imaging is also required to see for the reduction of
the bulk of the pulvinar which imposes on the proper reduction. If
there remains residual subluxation due to increased pulvinar fat,
majority of cases resolve without therapy. Associated labral tear or
degeneration can also be evaluated on MRI. Long term follow up MR
imaging is required in cases of painful hip to know the cause which is
attributed to the original pathology or avascular necrosis to plan for
further management.
Differential diagnosis
Very few differentials of DDH are there on imaging including post
traumatic and post infective dislocated. MRI also plays a significant
role in differentiating DDH from post infective sequalae of dislocated
head. Non visualisation of ossific nucleus with dislocation of femoral
head, altered marrow signal intensity, inflammatory changes in
adjacent muscles and significant joint effusion helps in differentiating
post infective dislocated head from DDH (Figure 9).
Conclusion
With recent advancement in orthopaedic imaging technique, MRI
Figure 9: Septic arthritis of right hip .T2W FS coronal image shows superiorly
dislocated head with joint effusion on right side (arrow) with edema in adjacent
muscle sequalae to infection.

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has assumed an important role in the early detection and evaluation
of DDH especially in children less than 6 months when the ossific
nucleus is not seen on conventional x-ray. MR scanning is useful in
the pre as well as post operative imaging in DDH. MRI is useful in
looking for causes of intrinsic and extrinsic causes of failed reduction.
Depending on the acetabular coverage, pre operative MRI also helps
in the management to go for the conservative reduction or osteotomy
to increase the acetabular coverage. With dynamic contrast enhanced
MRI, MRI has the ability to determine the vascularity of the femoral
head after reduction to identify the hips which are at increased risk
of ischemia and subsequent AVN which can further lead to the
development of AVN which is reversible compared to the months it
takes to manifest radiographically. Post operative MRI is also useful
in evaluating the adequacy of closed reduction. However limitations
include need for proper sedation due to long scanning, cost and the
MR compatible implants in post operative cases.
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Citation: Sherwani P, Vire A, Anand R and Aggarwal A. Utility of MR Imaging in Developmental Dysplasia of Hip.
Austin J Radiol. 2016; 3(3): 1052.
Austin J Radiol - Volume 3 Issue 3 - 2016
ISSN : 2473-0637 | www.austinpublishinggroup.com
Sherwani et al. © All rights are reserved